Similar to a soft handover in UMTS (UMTS=Universal Mobile Telecommunication Systems), CoMP transmissions (CoMP=Cooperative Multipoint) and CoMP receptions are effective transmission and reception schemes for obtaining an overall performance gain in radio communication systems such as LTE (LTE=Long Term Evolution). Thereby, the overall data rate can be increased without requiring additional frequency spectrum or without requiring an increase of transmit power. Especially users, that are located at the border between two radio cells or two radio sectors can benefit from CoMP transmissions and/or CoMP receptions.
CoMP transmission means a transmission of downlink data from a multipoint transmitter (e.g. two or more antenna systems of one or several base stations, which transmit same data) of a radio communication system to a mobile station. CoMP reception means a reception of uplink data at a multipoint receiver (e.g. two or more antenna systems of one or several base stations, which receive same data from a transmitter) of a radio communication system, which have been transmitted by a mobile station.
A radio communication system is operated usually at a specific IoT operational point (IoT=interference over thermal noise). The IoT is defined to be the total received interference power at a radio cell divided by the thermal noise power. The interference power consists of thermal noise plus the received power from all mobile station transmissions in other radio cells. For single-point to single-point transmissions from a mobile station to a single antenna system of the radio communication system, an IoT operational point of the radio communication system is much lower than an IoT operational point of a radio communication system in a CoMP mode. This means, that a mobile station transmitting for example in an uplink CoMP mode must be operated with different power control parameters than a further mobile station not transmitting in the uplink CoMP mode but transmitting uplink data by a single-point to single-point transmission. In a single-point to single-point transmission one or several antenna elements of an antenna system at the transmitter and one or several antenna elements of an antenna system at the receiver may be applied. Simultaneously operating a radio communication system with a first group of mobile stations operating in the uplink CoMP mode and a second group of mobile stations not operating in the uplink CoMP mode may degrade a performance and coverage area for mobile stations of the second group by using the high IoT operational point and reduces the overall performance by using the low IoT operational point.